This also works between subscriptions, using the exact same SQL username and password (e.g. sa with the same password).
Import / Export in Azure
Import and Export jobs use shared regional compute instances and have unpredictable and typically slow performance. I recommend you use SqlPackage if possible when importing and exporting database packages such as .bacpac and .dacpac.
SqlPackage in GitHub Actions
SqlPackage already comes with the hosted GitHub Actions workers.
An example of manually installing SqlPackage on Ubuntu Linux: